基于临界距离理论的TC4合金缺口试样 低循环疲劳寿命预测

对TC4合金缺口试样的临界距离和低循环疲劳寿命分别进行了分析和预测.研究了缺口临界距离与疲劳寿命、载荷比、应力集中系数的相关关系及其对寿命预测结果的影响.研究结果表明:TC4合金缺口试样的临界距离不仅与疲劳寿命有关,还与载荷比和应力集中系数相关.载荷比相同时,临界距离与疲劳寿命之间可采用幂函数经验公式来描述.载荷比为-1和0.1时,TC4合金缺口试样的临界距离-疲劳寿命曲线基本重合,当载荷比增大为0.5时,临界距离明显增大.载荷比和疲劳寿命相同时,临界距离与应力集中系数近似成反比关系.寿命预测结果表明:采用临界距离理论预测TC4合金缺口疲劳寿命时,要获得更准确的疲劳寿命预测结果,应同时考虑临界距离与疲劳寿命、载荷比以及应力集中系数等因素的相关性. 

LCF life prediction for TC4 alloy notched specimens based on theory of critical distance

Low cycle fatigue (LCF) life prediction and critical distance analysis for TC4 alloy notched specimens were conducted.The correlation between the critical distance and fatigue life,load ratio,stress concentration factor and their influence on the fatigue life prediction were studied.The result suggests that the critical distance of TC4 alloy is not only related to the fatigue life,but also to the load ratio and stress concentrate factor.For the same load ratio,the power function can be used to describe the relationship between the critical distance and the fatigue life.For TC4 alloy notched specimens,when the load ratios were -1 and 0.1,the critical distance-fatigue life curves almost coincide;when the load ratios rose up to R=0.5,the critical distance increased obviously.For the same load ratio and fatigue life,the critical distance of TC4 alloy notched specimens was approximately inverse to the stress concentrate factor.Life prediction results show that the correlation between critical distance and fatigue life,load ratio,stress concentration factor must be considered to obtain more accurate fatigue life prediction for notched TC4 alloy using the theory of critical distance.